In contrast to fluorescent lamps and high-power sodium lamps, the use of light-emitting diode (LED) lamps enables the control of not only photosynthetic photon flux density (PPFD) at the plant level, but also the relative spectral photon flux density distribution (RSPD) of light because of the variety, even at different times of day, of producible light emitted by LEDs of different types. Effects of the spectral photon flux density on plant growth and morphology have been investigated using several types of LEDs and plant species. However, few studies on lighting methods with time-varying PPFD or RSPD have been published to date. In this paper, we summarize the effects of time-varying PPFD on the net photosynthetic rate (P_n) and those of time-varying RSPD on plant growth and morphology. Detailed modeling studies have been conducted on the reactions of the photosynthetic pathway under time-varying PPFD at a cycle of milliseconds to seconds. The results of these modeling studies and actual measurements of P_n under pulsed light clearly indicate that pulsed light is not advantageous to improve P_n. Although the integrated PPFD of blue and red light was unchanged, the growth of leaf lettuce was promoted by asynchronous irradiation with blue light and red light compared with growth under simultaneous irradiation. We think that blue-light monochromatic irradiation promotes leaf elongation through leaf expansion as a primary factor in the enhancement of plant growth. In addition, changes in leaf photosynthetic capacity caused by blue-light monochromatic irradiation may be involved in plant growth promotion. An increasing number of studies have investigated the effects of time-varying RSPD on plants. However, the mechanisms underlying these effects remain to be elucidated.

与荧光灯和大功率钠灯相比，使用发光二极管（LED）灯不仅可以控制植物水平的光合光子通量密度（PPFD），而且可以控制相对光谱光子通量密度分布（RSPD），因为即使在一天的不同时间，不同类型的LED发出的可产生光的种类也不同。使用几种类型的LED和植物物种已经研究了光谱光子通量密度对植物生长和形态的影响。然而，迄今为止，很少有关于使用时变PPFD或RSPD的照明方法的研究。在本文中，我们总结了时变PPFD对净光合速率（P _n）以及随植物生长和形态变化的RSPD的那些。在时变PPFD下，以毫秒至秒的周期对光合途径的反应进行了详细的建模研究。这些建模研究的结果和脉冲光下P _n的实际测量结果清楚地表明，脉冲光不利于改善P _n。尽管蓝光和红光的综合PPFD没有变化，但是与同时照射下的生长相比，蓝光和红光的异步照射促进了莴苣的生长。我们认为，蓝光单色辐射通过叶片扩张来促进叶片伸长，这是增强植物生长的主要因素。另外，由蓝光单色辐射引起的叶片光合能力的变化可能与植物生长促进有关。越来越多的研究调查了时变RSPD对植物的影响。但是，这些作用的潜在机制仍有待阐明。